This invention relates to a method of and an apparatus for grinding surface portions of thick plates, and its object is to permit the grinder wheel to be naturally or smoothly raised for separation from and lowered into contact with the workpiece near the turning points of its oscillatory or swinging motion when removing local irregularities or other imperfections from the surface of thick plates, so as to eliminate unevenness at the opposite ends of the ground area and obtain a smoothly continuous finished surface while providing a constant grinding pressure to accommodate for large warp of the workpiece plate and irrespective of the wear of the grinding wheel.
Heretofore, the removal of local irregularities or imperfections from the surface of this type of thick plate having comparatively broad areas has been achieved with a hand grinder or wagon grinder, and it has been in practice to manually accomplish the swinging of the grind stone or grinding wheel and manually bring it into contact with and separate it from the workpiece. However, this operation not only requires extremely high skill or dexterity, but also poses difficulties in obtaining a uniform quality of finish.
In view of the above inconveniences, according to the present invention the grinding wheel is imparted with a motion that automatically raises it off and brings it into contact with the workpiece being ground at the turning points in its swinging or oscillatory movement, while also permitting a constant grinding pressure to be provided for grinding even if there is large warp in the thick plate of the workpiece and irrespective of the wear of the grinding wheel. An embodiment of the invention will now be described with reference to the accompanying drawings.